Scientists made a series of high-altitude flights this month from NASA’s Dryden Flight Research Center in Palmdale, Calif., demonstrating the scientific feasibility of surface elevation measurements to be made by one of the agency’s future Earth observing satellites, the Ice, Cloud and land Elevation Satellite-2 (ICESat-2). The first image (above) returned from a flight Dec. 8 clearly shows a layer of cirrus clouds and a high density of data points outlining surface elevation over California. Data in the image are preliminary and not for scientific use.

The data are from the Multiple Altimeter Beam Experimental Lidar (MABEL) instrument, assembled by a team led by ICESat-2 instrument scientist Matt McGill at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Tucked into the nose of the ER-2 aircraft (right) MABEL flew at an elevation of 65,000 feet (more than 12 miles) over five targets across the U.S. Southwest collecting surface elevation information similar to what will be collected by ICESat-2, scheduled for launch in January 2016.

“These were engineering test flights with intelligent science targets,” said Kelly Brunt, a polar scientist from Goddard who was in the field as a science liaison for flight planning. “We wanted to hit spectrum of targets that represent what the scientists are interested in, such as ocean water, fresh water, trees, snow, steep terrain and salt flats.

“The density of data collected is astounding, and will allow us to characterize what we see from space,” said Thorsten Markus, ICESat-2 project scientist and head of the Cryosphere Branch at Goddard.

Combined with the movie of swirling lights you might even have guessed some kind of spacecraft launch or radio tower.

In fact, both the sound and image are of completely natural origin. The movie shows what’s known as a pulsating aurora – a very common, but hard to see, weak aurora that blinks on and off up to 12 times per minute in the night sky.

The sound is of something no one knew was connected to these auroras until recently: a special kind of electromagnetic wave some 40,000 km higher in Earth’s magnetosphere called a chorus wave, since it sounds like birds chirping when played through a speaker.

How the pulsating auroras form has long been a mystery. Stable auroras form when electrons and ionized particles from the solar wind travel down magnetic field lines towards Earth. These collide with nitrogen and oxygen particles in the ionosphere, some100 km above Earth, and the collisions send out blue, green, and red photons to create the colorful light shows of the aurora.

But no one knew what could cause an aurora to turn into a strobe light until scientists at UCLA looked at data from NASA’s THEMIS spacecraft. They discovered that the auroras pulsed in sync to chorus waves far above Earth’s atmosphere. The chorus waves apparently drive the light-inducing solar wind particles down to Earth following its own unique beat.

Linking the two phenomena does more than explain the origins of the pulsating aurora. Using the electromagnetic waves and the aurora to define end points of magnetic field lines gives scientists a new tool to physically map Earth’s constantly changing magnetic field. Knowing the way that the magnetic field moves, in turn, is crucial for understanding space weather and phenomena that can threaten Earth-observing satellites.

Top Image: Pulsating aurora image taken on Oct 30, 2008 in Laukvik, Lofoten Islands, Norway. Courtesy of Jan Koeman. Middle Image: A snapshot of the pulsating aurora taken by a ground-based camera. The black square in the middle is the THEMIS spacecraft. Bottom Image: Schematic diagram showing aurora over North America and spacecraft in space (magenta) embedded in the energetic plasma source (blue cloud). These two regions are connected by the Earth’s magnetic field line. Energetic plasma interacts with waves (red) and precipitate into the upper atmosphere (blue arrows) and generate aurora. The geometry of the plasma cloud determines the aurora shape. Courtesy of Toshi Nishimura

Meanwhile, six months after the spill, and long after media and twitter chatter about it has subsided, scientists continue to parse out the details of the unprecedented event. I spent the afternoon yesterday in a session at AGU that highlighted the incredible array of resources the scientific community flung at the problem.

NASA is known best for its satellites (in this case, the iconic imagery of the spill captured by the MODIS instruments). Yet, as we’ve pointed out on this blog before, satellites aren’t the only tool that NASA’s earth scientists have at their disposal. In the midst of the oil spill crisis, NASA scrambled a number of aircraft bearing instruments that have a played key roles in sorting out the dynamics of the spill.

During the AGU session, Michael Freilich, director of NASA’s earth science division, emphasized the novel contributions of an airborne instrument called the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), a spectrometer that flew aboard the ER-2, a civilian version of the famous U-2 spy planes, and the Twin Otter, a much smaller propeller plan that flies at a lower altitude.

At AGU, Freilich outlined the AVIRIS contributions:

Flights were planned to do coastal ecosystem work because the hyperspectral measurements can be used to classify vegetation and to determine the impact of the oil on that vegetation, as well as to map the volume of the oil in the upper ocean over the oceanic portions of the slick. In a couple of weeks, AVIRIS flights took as much data as we usually take in an entire year or more. And whereas it usually takes two-to-three months for the AVIRIS data to be processed, calibrated, and distributed, the team working at Johnson, very early on, got it down to providing imagery and calibrated radiances to between 6 to 12 hours after a flight. Those measurements were then given to NOAA and USGS scientists, as well as analyzed by NASA and academic scientists.

The director of the United States Geological Survey Marcia McNutt also praised AVIRIS during the session for its ability to image oil on the surface, and noted that AVIRIS helped determine the lower bound on the amount of oil released. “[It] did an excellent job of determining the amount of oil that was likely to impact the shoreline,” she said. “We are very grateful for the support we received from NASA for this work,” she said.

The crux of the problem: there are more than 15,000 individual abstracts to pick through, not to mention no small number of other lectures, plenary sessions, and events vying for attention. It is simple enough if you’re a scientist — just focus on the talks and posters related to your area of expertise. It’s a bit trickier if you happen to be a science writer trying extract the zeitgeist of the whole meeting. Indeed, on deadline, the exercise of choosing talks can be near maddening.

To figure out how to focus the bulk of my time and energy this year, I decided to try something new. Rather than simply thumbing through the master list of talks highlighting the those that looked interesting, I am opting for a more quantitative approach. Last night, I downloaded a handy program called Word Counter that, among other things, can tally up the most frequently-used words in a document.

I ran the titles for each day’s sessions (both posters and oral) through the program to see what turned up. The output was fascinating: a bird’s eye view of the topics that scientists are talking about the most. Take the Monday morning session. Word Counter reports that the five most cited words are water (109 mentions), aerosol (100), climate (77), mantle (67), and ice (66). Not exactly shockers (though I wouldn’t have expected aerosol to be so high), but knowing that what these most “buzzed-about” topics did make it much more interesting to go back and pick through abstracts.

Stayed tuned. At the end of the meeting, I will be post more keyword results from Word Counter. Also, a hat tip to the Highly Allochthonous blog for this post, which was the source of inspiration for the graphic above.

It’s not just the hydrology talks; water in all its various forms (vapor, ice, liquid) come up in a broad range of contexts (agriculture, clouds, water quality) Topping my list as most interesting: The set of posters exploring connections between hydrology and human health. Who knew researchers were trying to predict cholera outbreaks using remote sensing?

Aerosols (read this if you’re not familiar with why the small airborne particles matter) are a topic every student of earth science ought to know something about. The particles have become one of the hottest areas of research among scientists as they’re not particularly well-understood, yet have a big impacts on human health and climate. There’s a cloud-aerosol session worth swinging by to find out how the problematic particles modify clouds. If I have time, I also plan to stop by a sessions about mineral dust. There’s a lot more dust wafting about in the air than you’d think, and this is your chance to find out what it might mean for the climate.

Most Mentioned Places: California (46), Arctic (35), China (28)The summer’s CalNex campaign has produced a flood of studies about the Golden State; many of them focus on parsing out the relationship between air quality and climate. The Arctic is another big theme, particularly in a session about the future of polar science. In China, scientists dig deep beneath the continent for clues about the crust in Asia.

Fulgurites form in a flash – when lightning strikes simple beach sand or desert soil on a surface that conducts electricity, such as water, at a temperature of at least 3,270 degrees Fahrenheit (1,800 degrees Celsius). The extreme heat forces the grains of sand (or sometimes soil or rock) to melt and fuse together. The product cools, producing a hollowed glass structure that mimics the appearance of a tree root or large branch.

Why the odd shape, you might wonder? The lightning bolt fans out in several directions as it hits the water in an attempt to release its energy. The length of each “branch” of a fulgurite is equivalent to how quickly each path of the lightning strike exhausted itself of energy.

Fulgurites are rare enough to cost hundreds of dollars depending on size and shape, and intriguing enough to be the focus of research projects. A 2009 University of Arizona-Tucson study , for example, found that fulgurites contain a partially-oxidized form of phosphorus called phosphite that early microbes may have thrived on as a nutrient.

This summer, a NASA-funded study revealed that fulgurites can experience a range of temperatures during formation.

So, next time you want to impress your friends with arcane but fascinating trivia, ask if they know what a fulgurite is. When they scratch their heads and offer blank stares, boot up your laptop, show them our What On Earth #5 post and explain this fluke of nature. You’re sure to dazzle them with your extra-ordinary intelligence and one of the marvels of science.